A Dinosaur's Ancestor Walked Here...250 Million Years Ago

A dinosaur skeleton at the American Museum of Natural History, in New York. This animal lived tens of millions of years after its recently discovered predecessor. Photo: arabani under a Creative Commons license.

250 million years ago, a dinosaur, walking on four legs and about the size of a house cat, walked through a quarry in what is now Poland. On Wednesday, the journal Proceedings of the Royal Society B published the findings of its fossilized footprints, the New York Times reported. To be precise, the creature that roamed the Polish quarry did not fit all the criteria that define a dinosaur (a general term for a wide variety of species), but Stephen Brusatte, a Columbia University graduate student and the lead author of the journal article, says that it and the dinosaurs that evolved from it had much in common.While no actual bones have been found in the area (and researchers are optimistic), a lot has been learned from the footprints, the Times reported:

The findings indicate that dinosaurs, which died out in a meteor impact 65 million years ago, originally arose to fill ecological niches opened by an earlier, even greater mass extinction.

"It's definitely exciting," said Sterling Nesbitt, a researcher at the Burke Museum at the University of Washington. Dr. Nesbitt said that it was often hard to draw convincing conclusions about animals just from their footprints, but that Mr. Brusatte and his colleagues "put the best argument that anyone has ever put forth about early dinosaur tracks." He added, "And I think they're right."

The mass extinction that opened the door to dinosaurs occurred shortly before the recently-found footprints were made, at the close of the Permian period, about 251 million years ago. Unlike the extinction event that wiped out much of the life on Earth 65 million years ago, this one had nothing to do with a comet. The culprit? Climate change.